As generally known, a stay strand comprises a wire or a plurality of twisted wires intended to be tensioned for the purpose, in particular, of prestressing a body made of concrete or for suspending a civil engineering structure such as a bridge.
To accomplish tensioning, the stay strand is first locked or clamped in an anchoring block by means of a jaw or jaws fitted into the block to grip the strand by friction or traction with the strand and at least partly by application of an axial thrust or force against a large base of the jaw. Such axial thrust effects a radial clamping force on the strand effected typically by a frustoconical or cone jaw configuration fitted into a compatible opening in the anchor block. In order to guarantee that the strand does not slip in relation to the jaw surrounding it, a securing operation, called overlocking, guarantees that the jaw will be held around the strand during the lifetime of the civil engineering structure on which the said strand is tensioned.
This overlocking operation is currently carried out by means of hammer blows applied directly to the large base of the jaw in order to displace it by a few millimetres axially within its housing or anchoring block so as to guarantee radial prestressing force on the strand. Nevertheless, this overlocking operation, carried out by an operator using a hammer to strike blows on the jaw, does not guarantee with certainty that the displacement of the anchoring jaw within its housing or anchoring block has been sufficient for the jaw to find a so-called final position, that is to say a position that the jaw is intended to find during the maximum loading tolerated by the stay strand.
Moreover, a securing operation by means of hammer blows is not generally suitable when the anchoring jaw is difficult to access, in particular in cramped civil engineering structures.